A variety of potent, broad-spectrum penicillins and cepharosporins are known and have been used as antibiotics for therapeutic purposes. They are very effective in treating various infectious diseases. In the medical field, effective antimicrobial agents have been put to practical use one after another and, accordingly, pathogenic bacteria have acquired resistance thereto following introduction of each antimicrobial agent. Such a situation always requires a further new antimicrobial agent. Such is also the case with the above-mentioned penicillins and cepharosporins and, as a result of the development of resistance thereto in bacteria, the penicillins and cepharosporins currently in use are already not always wholly satisfactory from the standpoint of antimicrobial activity, pharmacokinetics and/or safety.
Thienamycin is one of known carbapenems (JP-A-51-73191) (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), and U.S. Pat. No. 3,950,357. It is effective even against bacteria resistant to penicillin and cepharosporin antibiotics and thus has a broad antibacterial spectrum. Therefore, since the discovery of thienamycin, efforts have been made to synthesize carbapenem derivatives and compounds having skeletons similar to thienamycin. However, so-far the known carbapenem and penem antibiotics are physico-chemically unstable and are readily degradable upon exposure to kidney dehydropeptidase, among other enzymes; no compounds have been identified as being useful as drugs.
As mentioned above, while antibiotics are effective in the treatment of infectious diseases, there is the problem of development of resistance in bacteria. Those penicillin and cepharosporin antibiotics which have been used universally because of their having a broad antibacterial spectrum are no exception and, as resistance thereto develops in bacteria, they become targets of criticism from the standpoint of their antibacterial spectrum among other characteristics.